Recently, a handsfree function using Bluetooth has been installed in a vehicle in order to prevent inconvenience and accidents due to cell phone conversation. The handsfree function is embodied to output voice of the other user through a speaker of the vehicle and to input driver's voice through a microphone installed in the vehicle.
In general, a microphone includes only one core for receiving actual sound. However, the core of the microphone has directivity, and thus efficiency for receiving sound input within a specific direction range and efficiency for receiving sound input within other directions are different (that is, receive sensitivity for sound input in the remaining directions is degraded).
Accordingly, when receive sensitivity at either a driver seat or driver and passenger seats is considered, a microphone is arranged as shown in FIG. 1.
FIGS. 1A and 1B are diagrams illustrating configurations of a microphone located inside a general vehicle.
Referring to FIG. 1A, when a handsfree function is installed for only a driver seat, one microphone 110 is disposed to achieve the highest receive sensitivity upon being directed toward a driver seat. In this case, it may be said that audio beamforming is achieved toward a driver seat.
When a passenger of a passenger seat as well as a driver is considered, as shown in FIG. 1B, if a microphone 110A toward a driver seat and a microphone 110B toward the passenger seat are separately installed so as to form beamforming for each position of the passengers, voice input could be optimized.
General microphone arrangement like FIG. 1B requires plural microphones separately arranged for each position inside a vehicle. It has been a problem that the microphone arrangement could not consider factors causing difference and direction for beamforming, such as occupant's seat location or occupant's physique in a vehicle.